Monday, November 5, 2007
19-13

Determination of Hydrogen Ion Concentration in Soil Using a Plastic Tube Silver Electrode with a Tribenzylamine Based Membrane.

Alfred Conklin, Wilmington Col., Wilmington College, 251 Luclovic St. Box 1304, Wilmington, OH 45177 and Kimberly M. Nelson, Agriculture, Wilmington College, 1870 Quaker Way, Wilmington, OH 45177.

The assessment of hydrogen ion concentration(pH) is an essential measurement in numerous fields. Traditionally, pH is evaluated using an electrode with a glass membrane that serves as the proton detector once an exchange occurs through the outer solvated layer of the glass. There are many disadvantages to glass electrodes such as: breakage, scratches, glass and electrical properties change over time, and the finite lifetime of a glass electrode. A pH electrode was constructed from 2 mm plastic tubing, silver wire, 0.1 M hydrochloric acid as a filling solution, and a tribenzylamine based membrane. This electrode was used to obtain 50 measurements and concurrently compared with a commercial pH electrode over a pH range of 3.9 to 10.1. Statistical analysis gave an R2 of 0.998 and a slope of 54 between the sets of measurements. Measurement of soil pH using standard methods with this method of measurement with the same electrodes was also performed.